Buoyancy effect on the heat convection in vertical channels with fin array at low Reynolds numbers

Numerical study of the buoyancy effect on the flow pattern and heat transfer in an asymmetricheating channel with a series of conductive fins is presented. These identical fins are attached on the relatively hotter wall at equal steamwise spaces so that a periodic flow character prevails in the fullydeveloped region. It is found that within one module, in addition to the typical recirculating flow at the rear of each fin, a secondary recirculating vortex appears near the colder wall when the heating of hotter wall is sufficiently intense. The strength and pattern of the secondary vortex are found to be governed by Grashof number, Reynolds number, and the geometric parameters such as fin pitch, fin height and the inclination angle of channel. Also, based on the obtained velocity and temperature solutions, the values of the pressure gradient and overall heat transfer within the solution domain are further calculated and provided. Meanwhile, buoyancy-assisted flow reversal phenomenon in the unfinned channel is also discussed and a very different feature in the flow reversal pattern between finned and unfinned channels can then be observed.